This book explores and discusses various aspects of intelligent systems technologies and their applications. It constitutes the thoroughly refereed post-conference proceedings of the 4th International Symposium on Intelligent Systems Technologies and Applications (ISTA18), September 19-22, 2018, Bangalore, India. All submissions were evaluated on the basis of their significance, novelty, and technical quality. This book contains 20 papers selected for presentation at the Symposium. The book is chiefly intended for, and offers a valuable resource for, researchers and scientists engaged in various fields involving intelligent systems.